Our interest has been first to study host-pathogen interactions between the classical periodontal pathogen P.gingivalis and antigen presenting cells of myeloid lineage and second to begin to characterize the nature of the T cell response driven by this pathogen. For this purpose we investigated the early transcriptional signatures and subsequent proteomic responses to the periodontal pathogen, Porphyromonas gingivalis (Pg) in donor-matched human blood monocytes, differentiated DC and macrophages exposed to Pg bacteria and its LPS. In our ongoing studies we are investigating the nature of the T helper cell response initiated by P. gingivalis in vitro and in vivo in an effort to uncover host molecules and cell populations which may be key in the pathogenesis of disease and which may ultimately be candidate targets for future therapeutic intervention.